As a rule, modern motor vehicles are provided with a self-supporting body, which, compared with a body mounted on a frame, makes possible a weight and costs reduction. In the self-supporting body, the components in their entirety absorb the introduced forces, wherein the stiffness of the body is achieved through hollow profiles and a compact outer sheet metal skin. Usually, the hollow profiles are produced from sheet steel, wherein for the purpose of the weight reduction, light metal materials are also employed.
In a typical design, self-supporting bodies comprise an underbody closing off the passenger cell towards the bottom, which is connected to the vehicle roof via vertical braces (pillars). In the region of the underbody, two side sills running in longitudinal direction and a center tunnel extending along the center longitudinal axis are provided, which are connected to one another by cross members. The center tunnel extends from a front wall separating the front body structure from the passenger cell to the rear as far as to the heel plate, which creates a transition between the floor panels of the passenger cell and the floor panels in the region of the trunk located higher up. The body components between the two side sills are mostly called “floor assembly”.
On the front end of the floor assembly, a frame-like structure (“front frame”) is located, which is assembled from load-bearing profile parts and serves for the stiffening of the front body structure. Exactly such a frame-like structure (“rear frame”) is located to the back of the floor assembly and serves for the stiffening of the rear body structure located behind the passenger cell. Both front as well as rear frames each have two side members extending in vehicle longitudinal direction, which are arranged on both sides of the center longitudinal axis of the vehicle and are rigidly connected to one another via cross members. In the overall construction, the side members are connected to the two side sills and the floor assembly, as a result of which a front and rear crash load path respectively is formed, so that the forces that occur during a vehicle collision can be introduced into the underbody and in particular into the side sill structure.
Before the background of increasingly more stringent legal regulations regarding the pollutant output of motor vehicles, it is desirable to make the vehicles as light as possible in order to reduce the overall fuel consumption. On the other hand, the body has to be stiff enough so that it is pushed in as little as possible for protecting the vehicle occupants in the event of a collision. In this regard it is desirable to achieve as high as possible a twisting or torsional stiffness of the body with as low a vehicle weight as possible. In addition, the fatigue behavior of the body is to satisfy the high requirements that are made on the running performance of modern motor vehicles. A further important aspect is the possibility of producing the body in series production with preferably low production and material costs.
In contrast with this, at least one object herein consists in advantageously further developing the bodies of self-supporting bodies of motor vehicles known in the prior art. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.